//oled

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library.
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), ...
// On an arduino ESP8266:   D2(SDA)GPIO4,  D1(SCL)GPIO5, ...
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
//oled

const int TrigPin = 11;
const int EchoPin = 12;
float distance;

void startinfo() {
  display.clearDisplay();

  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.println(F("System"));
  display.setTextSize(2);
  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
  display.println("booting");

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.println("......");

  display.display();

}


void showinfo(String temp) {
  display.clearDisplay();

  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.println(F("Distance"));
  display.setTextSize(2);
  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
  display.println("CM: ");

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.println(temp);

  display.display();

}



void setup()
{ // 初始化串口通信及连接 SR04 的引脚
  Serial.begin(115200);
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Don't proceed, loop forever
  }

  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();
  delay(2000); // Pause for 2 seconds
  startinfo() ;
  delay(1000);

  pinMode(TrigPin, OUTPUT);
  // 要检测引脚上输入的脉冲宽度，需要先设置为输入状态
  pinMode(EchoPin, INPUT);
  Serial.println("Ultrasonic sensor:");
}
void loop()
{
  // 产生一个 10us 的高脉冲去触发 TrigPin
  digitalWrite(TrigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(TrigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(TrigPin, LOW);
  // 检测脉冲宽度，并计算出距离
  distance = pulseIn(EchoPin, HIGH) / 58.00;
  Serial.print(distance);
  Serial.print("cm");
  Serial.println();
  showinfo(String (distance));
  delay(1000);
}